On Windows 7 (64-bit), it was not possible to reproduce any infinite looping behavior with the supplied example code.

Specifically, with the two examples from Benjamin, the observed behavior when running them was the same under 2.7.8 and default (3.5):  a RuntimeError results with a message suggesting that the code perhaps needs to leverage the "if __name__ == '__main__'" idiom to avoid having both parent and all subsequent children processes starting up a new process because they're all unintentionally running the same lines of code intended only for the parent to run.  Adding that idiomatic test to each of the two examples permits them to run to a happy conclusion.  That is, in the case of the first example we make that one-line code change to read:
# ---
import multiprocessing

def f(m):
    print(m)

if __name__ == '__main__':
    p = multiprocessing.Process(target=f, args=('pouet',))
    p.start()
# ---

This would be a recommended practice on unix-y systems as well as Windows.

Aside: It was not possible to reproduce the issue injected by Darren either -- perhaps the example code provided was not quite what he intended.

The infinite looping behavior described in the original issue description might well have been reproducible in much earlier releases.  In the current default (3.5) branch (or in 2.7.8), it is no longer possible to reproduce.  I'm tempted to mark this as "out of date" but instead will opt for "works for me" and close the issue.